A crawlspace in a structure is typically an area having low headroom and underlying a main portion of the structure. Typically, crawlspaces are provided, rather than a full basement structure, to reduce the cost of the structure. Since reduction of cost is an objective of such construction methods, the surface of the crawlspace is usually left unsealed and is, simply, a dirt surface.
Such unsealed dirt surfaces have a number of disadvantages. These include the promotion of dry rot in the wood members of the overlying structure and the provision of a hospitable climate for mildew, mold, and fungus which can adversely affect wallpaper, paint, and cloth materials beyond restoration and which can create unhealthy living conditions for occupants of the structure. Furthermore, resulting dampness and musty odor create uncomfortable living conditions and an unpleasant scent. Allergies can be aggravated by pollen and/or dust being circulated from the crawlspace through the ventilation system in the structure. Radon gas can easily enter the structure through the dirt surface of the crawlspace. Additionally, such crawlspaces are breeding grounds for a variety of vermin, rodents, and insects which are nuisances and which also pose health problems. Another disadvantage of an unsealed crawlspace is that heat is readily lost to the dirt surface. Even when sealed with conventional structural concrete mixtures, the heat loss problem is not greatly reduced. Also, structural concrete is somewhat porous and does not eliminate moisture.
In spite of the above disadvantages of unsealed crawlspaces, many remain in that condition because of the difficulty and expense of sealing the surfaces of the crawlspaces. This is because the only known method of sealing such spaces is to place a layer of structural concrete on the surface, but this is often very difficult and expensive using conventional techniques since accessibility and headroom are restricted by such crawlspaces and the conventional heavy structural concrete cannot be placed using conventional equipment, such as chutes and wheelbarrows. In some cases, pushing heavy buckets of concrete across the dirt surface and then dumping them, is the only procedure by which concrete can be placed. In other such cases, the interior of the structure and fixtures, as well as furniture therein, may be damaged if the structural concrete must be hauled through the interior of the structure to reach an access opening to the crawlspaces. Sometimes, the placement of the structural concrete results in unavoidable and/or unintentional damage to landscaping around the structure.
A further problem in the dispatch of conventional, structural concrete, especially on non-level surfaces of the crawlspace, is the flowing of the concrete after pouring to the lowest spot or levels. This leads to problems in areas of the crawlspace that remain uncovered, or have an insufficient amount of concrete covering on the ground surface.